Restenosis of the coronary artery develops in up to 40% of the patients who undergo coronary angioplasty. The development of restenosis imposes a major therapeutic and economic disadvantage to the commonly employed coronary angioplasty. The recent introduction of coronary atherectomy enables us to obtain coronary artery specimens for research purposes as a by-product of the therapeutic procedure. Study of the human coronary artery specimens, both of patients with restenosis and of patients with primary atheromata, will provide us with the opportunity to improve our understanding of restenosis and atherosclerosis. The present study was initiated to test the hypothesis that post angioplasty restenosis is mediated by growth factors and/or their receptors. We hypothesize that the mechanical trauma to the coronary artery and the exposure of vessel wall elements to the different components of the blood induce increased expression of growth factors and/or their receptors: hence, the induction of smooth cell proliferation and migration. Human coronary atherectomy specimen will be stained for different cellular and matrix content. The density of receptors to FGF and TGF Beta will be studied by the use of immunocytochemistry methods. Primary atheromata specimens will be compared to specimens obtained from patients with post angioplasty restenosis and the density of growth factors receptors will be quantitated.